Back to EveryPatent.com
| United States Patent |
5,264,653
|
|
Tabei
, et al.
|
November 23, 1993
|
Process for purifying 1,1,3,4,4,6-hexamethyltetralin
Abstract
A process for purifying 1,1,3,4,4,6-hexamethyltetralin is disclosed
comprising melting crude 1,1,3,4,4,6-hexamethyltetralin in methanol with
heating, cooling the resulting suspension, and adding seed crystals at a
temperature of 45.degree.-60.degree. C.; as well as a process for
purifying 1,1,3,4,4,6-hexamethyltetralin comprising recrystallizing crude
1,1,3,4,4,6-hexamethyltetralin from a mixed solvent of methanol and a
solvent capable of easily dissolving 1,1,3,4,4,6-hexamethyltetralin, the
proportion of this solvent being 10 to 25% by weight based on the weight
of methanol. These processes make it possible to obtain
1,1,3,4,4,6-hexamethyltetralin of high purity easily with high recovery by
purifying crude 1,1,3,4,4,6-hexamethyltetralin.
| Inventors:
|
Tabei; Nobuaki (Yokohama, JP);
Sato; Hiroshi (Niihama, JP)
|
| Assignee:
|
Sumitomo Chemical Company, Limited (Osaka, JP)
|
| Appl. No.:
|
953229 |
| Filed:
|
September 30, 1992 |
Foreign Application Priority Data
| Current U.S. Class: |
585/817; 585/812; 585/813; 585/815; 585/816 |
| Intern'l Class: |
C07C 007/14 |
| Field of Search: |
585/815,816,817,812,813
|
References Cited
U.S. Patent Documents
| 3856875 | Dec., 1974 | Wood et al. | 260/668.
|
| 4284818 | Aug., 1981 | Sato et al. | 585/411.
|
| 5079386 | Jan., 1992 | Meakins et al. | 585/409.
|
| Foreign Patent Documents |
| 0393742 | Apr., 1990 | EP.
| |
Other References
Chem. Abstracts, vol. 97, No. 5, Aug. 2, 1982, Nitto Riken Industries, p.
545.
|
Primary Examiner: McFarlane; Anthony
Assistant Examiner: Phan; Nhat D.
Attorney, Agent or Firm: Birch, Stewart, Kolasch & Birch
Claims
What is claimed is:
1. A process for purifying 1,1,3,4,4,6-hexamethyltetralin comprising
melting crude 1,1,3,4,4,6-hexamethyltetralin in methanol with heating,
cooling the resulting suspension, adding seed crystals of
1,1,3,4,4,6-hexamethyltetralin to said cooled suspension at a temperature
of 45.degree.-60.degree. C. and cooling the resulting mixture to obtain
crystals of 1,1,3,4,4,6-hexamethyltetralin.
2. The process for purifying 1,1,3,4,4,6-hexamethyltetralin according to
claim 1 which further comprises separating the crystals and then washing
the crystals with methanol.
3. The process for purifying 1,1,3,4,4,6-hexamethyltetralin according to
claim 1, wherein the cooling is conducted at a rate of 1.degree. C. per 1
to 10 minutes.
4. The process for purifying 1,1,3,4,4,6-hexamethyltetralin according to
claim 1 or 3, wherein the cooling of the mixture is effected until the
temperature of the mixture is 0-20.degree. C.
5. The process for purifying 1,1,3,4,4,6-hexamethyltetralin according to
claim 1, wherein said methanol is present in an amount of 1.5 to 2 parts
by weight per part by weight of crude 1,1,3,4,4,6-hexamethyltetralin.
6. A process for purifying 1,1,3,4,4,6-hexamethyltetralin comprising
recrystallizing crude 1,1,3,4,4,6-hexamethyltetralin from a solution
mixture of methanol and a solvent capable of dissolving
1,1,3,4,4,6-hexamethyltetralin, said solvent being present in an amount of
10 to 25% by weight based on the weight of methanol to obtain crystals of
1,1,3,4,4,6-hexamethyltetralin.
7. The process of purifying 1,1,3,4,4,6-hexamethyltetralin according to
claim 6, wherein the recrystallizing is effected by dissolving
1,1,3,4,4,6-hexamethyltetralin in the solution mixture of methanol and a
solvent capable of dissolving 1,1,3,4,4,6-hexamethyltetralin with heating,
cooling the solution, adding seed crystals of
1,1,3,4,4,6-hexamethyltetralin to the cooled solution at a temperature of
45.degree.-60.degree. C. and then cooling the resulting mixture.
8. The process for purifying 1,1,3,4,4,6-hexamethyltetralin according to
claim 6 or 7, wherein cooling for the recrystallization is conducted at a
rate of 1.degree. C. per 1 to 10 minutes.
9. The process for purifying 1,1,3,4,4,6-hexamethyltetralin according to
claim 6 or 7, which further comprises separating the crystals of
1,1,3,4,4,6-hexamethyltetralin and then washing the crystals with a
solvent mixture containing methanol.
10. The process for purifying 1,1,3,4,4,6-hexamethyltetralin according to
claim 6, wherein the solvent capable of dissolving
1,1,3,4,4,6-hexamethyltetralin is at least one compound selected from the
group consisting of ethanol, propanol, butanol, acetone, methyl ethyl
ketone, methyl isobutyl ketone, dichloromethane, chloroform, carbon
tetrachloride, 1,1,1-trichloroethane, ethylene chloride,
tetrachloroethylene, 1,2,3-trichloropropane, benzene, toluene, xylene,
chlorobenzene and dichlorobenzene.
11. The process for purifying 1,1,3,4,4,6-hexamethyltetralin according to
claim 6, wherein said solution mixture is present in an amount of 1.5 to 2
parts by weight per part by weight of crude
1,1,3,4,4,6-hexamethyltetralin.
12. The process for purifying 1,1,3,4,4,6-hexamethyltetralin according to
claim 1 or 7 wherein the seed crystals are added at a temperature of
50-55.degree. C.
13. The process for purifying 1,1,3,4,4,6-hexamethyltetralin according to
claim 1 or 7, wherein the seed crystals are added in a proportion of 0.1
to 1% by weight based on the weight of crude
1,1,3,4,4,6-hexamethyltetralin.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a process for purifying
1,1,3,4,4,6-hexamethyltetralin (hereinafter referred to as HMT).
7-Acetyl-1,1,3,4,4,6-hexamethyltetralin obtained by acetylation of HMT is
used as a perfume for soap and cosmetics.
Japanese Patent Examined Publication No. 53-10057 describes a process
comprising producing HMT from p-cymene, removing a solvent ethylene
dichloride by distillation at atmospheric pressure, recovering the excess
p-cymene under reduced pressure, thereafter obtaining HMT as a colorless
distillate (purity: 95%) having a boiling point of 80.degree.-90.degree.
C. at a pressure of 1 mmHg, and then recrystallizing this HMT from an
equal amount of isopropanol.
Japanese Patent Examined Publication No. 63-64410 describes a process
comprising removing the solvent ethylene dichloride at atmospheric
pressure, recovering the excess p-cymene under reduced pressure,
thereafter obtaining crude HMT with a purity of 85.7%, and then
recrystallizing the crude HMT from isopropanol.
However, in the conventional processes, the purity of purified HMT is not
always high and the recovery is not sufficient, probably because
isopropanol is a solvent capable of easily dissolving HMT and hence the
amount of isopropanol used is limited.
SUMMARY OF THE INVENTION
In view of these circumstances, the present inventor earnestly investigated
a process for purifying HMT, and consequently found that HMT of high
purity can be obtained with high recovery by melting crude HMT in
methanol, followed by crystallization by cooling, or recrystallizing crude
HMT from a mixed solvent of methanol and a solvent capable of easily
dissolving HMT.
An object of the present invention is to provide a process for purifying
HMT to a high purity easily with high recovery.
Other objects and advantages of the present invention will become apparent
from the following description.
According to the present invention, there is provided a process for
purifying 1,1,3,4,4,6-hexamethyltetralin comprising melting crude
1,1,3,4,4,6-hexamethyltetralin in methanol with heating, cooling the
resulting suspension, and adding seed crystals at a temperature of
45.degree.-60.degree. C. to carry out crystallization; or a process for
purifying 1,1,3,4,4,6-hexamethyltetralin comprising recrystallizing crude
1,1,3,4,4,6-hexamethyltetralin from a mixed solvent of methanol and a
solvent capable of easily dissolving 1,1,3,4,4,6-hexamethyltetralin, the
proportion of this solvent being 10 to 20% by weight based on the weight
of methanol.
DETAIL DESCRIPTION OF THE INVENTION
The crude HMT used in the present invention is not critical. There may be
used, for example, HMT with a purity of about 85% obtained by removing
starting materials and a solvent from a reaction mixture obtained by
reacting p-cymene with 2,3-dimethyl-1-butene or neohexene, or HMT with a
purity of about 95% obtained by distilling the HMT with a purity of about
85%.
HMT is difficultly soluble in methanol, but easily soluble in alcohols such
as ethanol, isopropanol, n-propanol, n-butanol, etc.; ketones such as
acetone, methyl ethyl ketone, isobutyl ketone, etc.; halogenated aliphatic
hydrocarbons such as dichloromethane, chloroform, carbon tetrachloride,
1,1,1-trichloroethane, ethylene chloride, tetrachloroethylene,
1,2,3-trichloropropane, etc.; aromatic hydrocarbons such as benzene,
toluene, xylene, trimethylbenzene, etc.; and halogenated aromatic
hydrocarbons such as chlorobenzene, dichlorobenzene, etc.
In the process of the present invention using methanol alone as a solvent,
methanol is used in a proportion of approximately 1.5-2 parts by weight
per part by weight of crude HMT. When the amount of methanol used is below
the above range, the purity of purified HMT is not high. Also when the
amount is beyond the above range, the purity is not further improved in
proportion to the amount of methanol. Crude HMT is mixed with methanol and
then melted in methanol with heating to be suspended therein. In this
case, just one small portion of HMT is dissolved.
Then, the suspension is slowly cooled. The cooling is conducted at a rate
of 1.degree. C. per approximately 1-10 minutes. The cooling is preferably
slow because large crystals of high purity can be obtained. But, too slow
cooling is not desirable. Seed crystals of HMT are added at a temperature
of approximately 45.degree.-60.degree. C., preferably approximately
50.degree.-55.degree. C. When the temperature at the addition is too high,
the seed crystals are dissolved. When the temperature is too low, HMT
crystals are rapidly precipitated. Therefore, both of such temperatures
are not desirable. The seed crystals are added in a proportion of
approximately 0.1.degree.-1% by weight based on the weight of the crude
HMT. The powder of the seed crystals is usually used. When the seed
crystals are not added or the amount of the seed crystals added is too
small, HMT crystals are not sufficiently precipitated.
The suspension is cooled finally to approximately 0.degree.-20.degree. C.
Although the final temperature is not critical, it is a temperature at
which the precipitation of HMT crystals ceases substantially. The crystals
precipitated are separated by filtration, centrifugation or the like. The
crystals thus separated are preferably washed with methanol because
crystals with higher purity can be obtained by the washing.
In the process comprising recrystallization from a mixed solvent, there is
used a mixed solvent of methanol and any solvents capable of easily
dissolving HMT, for example, alcohols such as ethanol, isopropanol,
n-propanol, n-butanol, etc.; ketones such as acetone, methyl ethyl ketone,
isobutyl ketone, etc.; halogenated aliphatic hydrocarbons such as
dichloromethane, chloroform, carbon tetrachloride, 1,1,1-trichloroethane,
ethylene chloride, tetrachloroethylene, 1,2,3-trichloropropane, etc.;
aromatic hydrocarbons such as benzene, toluene, xylene, trimethylbenzene,
etc.; and halogenated aromatic hydrocarbons such as chlorobenzene,
dichlorobenzene, etc.
The solvent capable of easily dissolving HMT is used in a proportion of
approximately 10-25% by weight based on the weight of methanol. When the
amount is less than approximately 10%, it is difficult to dissolve HMT in
the mixed solvent. Also, when the amount is more than approximately 25%,
the recovery of HMT decrease. The mixed solvent is used in a proportion of
approximately 1.5-2 parts by weight per part by weight of crude HMT, as in
the case of using methanol alone. HMT and the mixed solvent are mixed and
heated to dissolve HMT in the mixed solvent. Then, the resulting solution
is cooled to precipitate HMT crystals. The cooling, seeding, etc. are
carried out in the same manner as in the case of using methanol alone.
Although the crystallization can be also carried out without seeding, it
is preferably carried out by seeding because seeding facilitates the
precipitation of crystals and their separation. After being separated, the
HMT crystals can be improved in purity by washing with methanol or the
mixed solvent containing methanol.
In the processes of the present invention, beautiful crystals ca be
obtained by growing crystals with slow stirring, but too slow stirring
results in settlement of crystals to the bottom of a vessel. Therefore,
the crystallization by cooling is carried out while stirring at a slow
rate at which crystals do not settle. Second recovery of crystals from a
filtrate after the separation of crystals is difficult because the
filtrate contains a large amount of tar. But, HMT of high purity can be
recovered by applying the process of the present invention to a residue
obtained by separating and recovering the tar by distillation. HMT with a
purity of 99.9% or more can be obtained by practicing the process of the
present invention repeatedly.
By the process of the present invention, 1,1,3,4,4,6-hexamethyltetralin can
easily be purified to a high purity with high recovery.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
EXAMPLES
The present invention is illustrated in detail with the following examples,
which should not be construed as limiting the scope of the invention.
EXAMPLE 1
Into a 3-liter jacketed separable flask equipped with a stirrer and a
condenser were charged 20.22 g of anhydrous aluminium chloride, 400.5 g of
p-cymene and 300 g of cyclohexane, and vigorously stirred. Then, a mixture
of 126 g of 2,3-dimethyl-1-butene, 156.9 g of t-butyl chloride and 300 g
of cyclohexane was added dropwise to the resulting suspension over a
period of 1.5 hours while maintaining the temperature of the suspension at
20.degree. C., to carry out the reaction. The reaction mixture was stirred
at the same temperature for another 10 minutes and then allowed to stand
to separate tar, whereby an organic layer was obtained. The organic layer
was washed successively with 600 g of water, 600 g of a 1% aqueous sodium
hydroxide solution and 600 g of water. The solvent was removed from the
organic layer by distillation at atmospheric pressure, after which the
excess p-cymene was recovered under reduced pressure. Thus, 251.6 g of
crude HMT with a purity of 86.0% was obtained.
In a 500-ml jacketed separable flask equipped with a stirrer and a
condenser were placed 40.0 g of the HMT with a purity of 86.0% and 80 g of
methanol. Then, the mixture in the flask was heated under reflux for 1
hour, after which the temperature of the mixture was reduced at a rate of
1.degree. C. per 3 minutes. When the temperature became 55.degree. C., 0.1
g of seed crystals of HMT were added. Subsequently, the temperature of the
resulting mixture was reduced at a rate of 1.degree. C. per 6 minutes. The
mixture was stirred at 0.degree. C. for 1 hour, after which the
precipitate thus formed was filtered by suction through a Buchner funnel.
After the filtration, the precipitate was washed with 20 g of methanol. In
this case, the stirring was vigorously conducted so as to prevent HMT and
the solvent from separating into two layers.
The crystals thus obtained were collected and the solvent was allowed to
evaporate by means of a vacuum pump. The amount of the purified HMT thus
obtained was 30.30 g, its purity 99.4%, and the recovery of HMT 87.7%.
The solvent was recovered from the filtrate, whereby 8.88 g of an oil was
obtained. The HMT content of the oil was 48.1%.
EXAMPLE 2
In a 500-ml jacketed separable flask equipped with a stirrer and a
condenser were p1aced 40.0 g cf HMT with a purity of 86.0%, 64 g of
methanol and 16.0 g of ethanol. Then, the mixture in the flask was heated
while refluxing methanol, to dissolve HMT. The temperature of the mixture
was reduced at a rate of 1.degree. C. per 3 minutes. When the temperature
became 55.degree. C., 0.1 g of seed crystals of HMT were added. Then, the
temperature of the resulting mixture was reduced at a rate of 1.degree. C.
per 6 minutes. The reaction mixture was stirred at 0.degree. C. for 1
hour, after which the precipitate thus formed was filtered by suction
through a Buchner funnel. After the filtration, the precipitate was washed
with 20 g of a mixed solvent of methanol and ethanol. During the above
precipitation of crystals, the mixture was stirred at a slow rate at which
crystals did not settle to the bottom of the flask.
The crystals thus obtained were collected and the solvent was allowed to
evaporate by means of a vacuum pump. The amount of the purified HMT thus
obtained was 30.86 g, its purity 99.1%, and the recovery of HMT 88.8%. The
solvent was recovered from the filtrate, whereby 8.94 g of an oil was
obtained. The HMT content of the oil was 45.6%.
EXAMPLE 3
The same procedure as in Example 2 was repeated except for stirring the
mixture at such a rate at which crystals settled. The amount of the
purified HMT thus obtained was 30.84 g, its purity 99.1%, and the recovery
of HMT 88.8%. The solvent was recovered from the filtrate, whereby 9.25 g
of an oil was obtained. The HMT content of the oil was 46.6%.
EXAMPLE 4
The same procedure as in Example 3 was repeated except for changing the
temperature at the addition of seed crystals and the final temperature to
50.degree. C. and 10.degree. C., respectively. The amount of the purified
HMT thus obtained was 31.25 g, its purity 99.2%, and the recovery of HMT
90.1%.
The solvent was recovered from the filtrate, whereby 9.05 g of an oil was
obtained. The HMT content of the oil was 40.5%.
EXAMPLE 5
In a 500-ml jacketed separable flask equipped with a stirrer and a
condenser were placed 40.0 g of HMT with a purity of 85.3% and 80 g of
methanol. Then, the mixture in the flask was heated under reflux for 1
hour, after which the temperature of the mixture was reduced at a rate of
1.degree. C. per 3 minutes. When the temperature became 55.degree. C., 0.1
g of seed crystals of HMT were added. Subsequently, the temperature of the
resulting mixture was reduced at a rate of 1.degree. C. per 3 minutes. The
mixture was stirred at 0.degree. C. for 1 hour, after which the
precipitate thus formed was filtered through a Buchner funnel. During the
above precipitation of crystals, the mixture was stirred at a slow rate at
which crystals did not settle to the bottom of the flask. The crystals
thus obtained were collected and the solvent was allowed to evaporate by
means of a vacuum pump. The amount of the purified HMT thus obtained was
31.55 g, its purity 96.5%, and the recovery of HMT 89.2%.
EXAMPLE 6
The same procedure as in Example 5 was repeated except for using a mixed
solvent of 64 g of methanol and 16 g of ethanol in place of methanol and
changing the final temperature to 5.degree. C. The purity of the purified
HMT thus obtained was 98.6%, and the recovery of HMT 88.5%.
EXAMPLE 7
The same procedure as in Example 5 was repeated except for using a mixed
solvent of 48 g of methanol and 12 g of ethanol in place of methanol. The
purity of the purified HMT thus obtained was 96.3%, and the recovery of
HMT 87.0%.
EXAMPLE 8
The same procedure as in Example 5 was repeated except for using a mixed
solvent of 72 g of methanol and 8 g of isopropanol in place of methanol.
The purity of the purified HMT thus obtained was 96.6%, and the recovery
of HMT 87.0%.
EXAMPLE 9
The same procedure as in Example 5 was repeated except for using a mixed
solvent of 54 g of methanol and 6 g of isopropanol in place of methanol.
The purity of the purified HMT thus obtained was 96.7%, and the recovery
of HMT 89.3%.
EXAMPLE 10
The same procedure as in Example 5 was repeated except for using a mixed
solvent of 72 g of methanol and 8 g of ethylene chloride in place of
methanol. The purity of the purified HMT thus obtained was 97.8%, and the
recovery of HMT 86.2%.
COMPARATIVE EXAMPLE 1
In a 500ml jacketed separable flask equipped with a stirrer and a condenser
were placed 40.0 g of HMT with a purity of 86.0% and 23 g of isopropanol.
The mixture in the flask was heated under reflux for 1 hour, after which
the temperature of the mixture was reduced at a rate of 1.degree. C. per 3
minutes. When the temperature became 50.degree. C., 0.1 g of seed crystals
of HMT were added. Then, the temperature of the resulting mixture was
reduced at a rate of 1.degree. C. per 3 minutes. The mixture was stirred
at 5.degree. C. for 1 hour, after which the precipitate formed was
filtered by suction through a Buchner funnel. During the above
precipitation of crystals, the mixture was stirred at such a rate at which
crystals did not settle to the bottom of the flask. The crystals thus
obtained were collected and the solvent was allowed to evaporate by means
of a vacuum pump. The amount of the purified HMT thus obtained was 29.03
g, its purity 94.4%, and the recovery of HMT 80.3%.
Top